Friedländer reaction in the synthesis of 2-(phosphoryl)alkyl-substituted 1,6-naphthyridines

First 2-(phosphoryl)alkyl-substituted 1,6-naphthyridines have been synthesized by the Friedländer reaction between 4-amino-3-formylpyridine and phosphorus-containing ketones; their structures have been confirmed by ¹H, ¹³C and ³¹P NMR spectroscopy and X-ray diffraction analysis.